GATA genotype and FY*B(-67T>C) polymorphism as a cheap and reliable tool to evaluate ethnicity in Brazilian patients submitted to autologous transplantation

Abstract Collecting high quality data on race and ethnicity is crucial for clinical research, notably in genetic association studies, to avoid confounding by different ethnic background among patients, a bias referred to as population stratification. In Brazil, to describe race we commonly use the National Institute of Geography and Statistics (IBGE) classification, so-called “self-declared color”, but it is acknowledged that defining ancestry by phenotypic characteristics, especially in countries with highly mixed population like Brazil, can be misleading. We aimed to evaluate the relationship between the GATA FY*B(-67T>C) polymorphism and self-declared race in Brazilian patients undergoing autologous transplantation and verify the feasibility of using this test as a more reliable tool to evaluate ethnicity in this population. Methods: We conducted a study to evaluate the association of candidate-gene polymorphisms and toxicities after autologous stem-cell transplantation (ASCT) in adult patients with lymphoma or myeloma from 2015 to 2021 in two Brazilian transplant centers. All patients with available DNA to study genetic polymorphisms were included. In this analysis we evaluate the association between GATA polymorphism and self-declared color in this cohort. Results: A total of 217 patients were included in this analysis. Median age at transplantation was 56 years (21-79) and 130 patients (59.9%) were male. Most patients were self-declared white (n=175, 80.6%) and the most common genotype was GATA67T/T (wild type/wild type) (n=142, 65.4%). Among the self-declared white patients, 73.1% were genotyped as GATA67T/T and 4.0% as GATA-67C/C, while among the non-white patients 21.4% were genotyped as GATA-67C/C (p<.001). The allele FY*B(-67T>C) frequency was 0.22 in the whole population; it was identified in 26.9% of the self-declared white patients and in 66.6% of the non-white (p<.001). Twelve-month overall survival was 86.6% (95% CI 79.9 - 91.2%), with no difference according to self-declared race (86.8% vs 85.5% for white and non-white patients, respectively, p=0.81) or the presence of the allele FY*B(-67T>C) (85.2% vs 89.9% for non-mutated and mutated patients, respectively, p=0.27). Conclusion: GATA FY*B(-67T>C) polymorphism is associated to self-declared race in Brazilian patients submitted to ASCT. Given the importance of correctly evaluating ancestry in genetic association studies in transplantation, GATA FY*B(-67T>C) polymorphism can be used as a more accurate tool in populations with mixed ethnic/racial background.